1. Field of the Invention
The invention relates to internal combustion engines and, more particularly, relates to a method and apparatus for emulating engine speed and position signals used to control engine operation.
2. Description of Related Art
It is sometimes desired to advance or retard engine rotational position signals in an internal combustion (IC) engine in order to control engine operation such as, for example, advancing or retarding fuel injection timing compared to the injection timing that would otherwise be implemented under prevailing engine operating conditions. For example, in a “dual fuel” or other “multi-fuel” engine fueled under at least some operating conditions by a diesel pilot ignited natural fuel charge, it is desirable to advance or retard the diesel injection timing compared to that which would be desired for a diesel-only engine in order to obtain desired combustion characteristics. Typically, software is employed to read the position sensors and relay the input signal with an angle-based delay. This technique, though effective, can only be used to retard fuel injection. Other techniques are available for both advancing and retarding fuel injection, but they are limited in their ability to advance fuel injecting timing because they necessarily rely on real-time or near-real time encoder data for their controls. An example of such a system is disclosed in British Published Application No. 2,437,098, the subject matter of which is hereby incorporated by reference in its entirety.
The need therefore has arisen to provide a simple and effective technique of advancing or retarding a control signal in an IC engine.